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Chapter 21 Carboxylic Acid Derivatives (continued)

Organic Chemistry , 6 th Edition L. G. Wade, Jr. Chapter 21 Carboxylic Acid Derivatives (continued). Jo Blackburn Richland College, Dallas, TX Dallas County Community College District ã 2006, Prentice Hall. =>. Hydrolysis of Acid Chlorides and Anhydrides.

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Chapter 21 Carboxylic Acid Derivatives (continued)

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  1. Organic Chemistry, 6th EditionL. G. Wade, Jr. Chapter 21Carboxylic Acid Derivatives(continued) Jo Blackburn Richland College, Dallas, TX Dallas County Community College District ã 2006,Prentice Hall

  2. => Hydrolysis of Acid Chlorides and Anhydrides • Hydrolysis occurs quickly, even in moist air with no acid or base catalyst. • Reagents must be protected from moisture. Chapter 21

  3. => Acid Hydrolysis of Esters • Reverse of Fischer esterification. • Reaches equilibrium. • Use a large excess of water. Chapter 21

  4. Saponification • Base-catalyzed hydrolysis of ester. • “Saponification” means “soap-making.” • Soaps are made by heating NaOH with a fat (triester of glycerol) to produce the sodium salt of a fatty acid - a soap. • One example of a soap is sodium stearate, Na+ -OOC(CH2)16CH3. => Chapter 21

  5. => Hydrolysis of Amides Prolonged heating in 6 M HCl or 40% aqueous NaOH is required. Chapter 21

  6. => Hydrolysis of Nitriles • Under mild conditions, nitriles hydrolyze to an amide. • Heating with aqueous acid or base will hydrolyze a nitrile to an acid. Chapter 21

  7. => Reduction to Alcohols Lithium aluminum hydride reduces acids, acid chlorides, and esters to primary alcohols. Chapter 21

  8. => Reduction to Aldehydes Acid chlorides will react with a weaker reducing agent to yield an aldehyde. Chapter 21

  9. => Reduction to Amines • Lithium aluminum hydride reduces amides and nitriles to amines. • Nitriles and 1 amides reduce to 1 amines. • A 2 amide reduces to a 2 amine. • A 3 amide reduces to a 3 amine. Chapter 21

  10. => Organometallic Reagents Grignard reagents and organolithium reagents add twice to acid chlorides and esters to give alcohols after protonation. Chapter 21

  11. => Grignard Reagentsand Nitriles A Grignard reagent or organolithium reagent attacks the cyano group to yield an imine which is hydrolyzed to a ketone. Chapter 21

  12. => Acid Chloride Synthesis • Use thionyl chloride, SOCl2, or oxalyl chloride, (COCl)2. • Other products are gases. Chapter 21

  13. acid anhydride => Acid Chloride Reactions (1) acid ester amide Chapter 21

  14. acylbenzene => Acid Chloride Reactions (2) 3° alcohol ketone 1° alcohol aldehyde Chapter 21 AlCl3

  15. => Industrial Synthesis of Acetic Anhydride • Four billion pounds/year produced. • Use high heat (750°C) and triethyl phosphate catalyst to produce ketene. Chapter 21

  16. => Lab Synthesisof Anhydrides • React acid chloride with carboxylic acid or carboxylate ion. • Heat dicarboxylic acids to form cyclic anhydrides. Chapter 21

  17. acylbenzene => Anhydride Reactions acid ester amide AlCl3 Chapter 21

  18. => Anhydride vs. Acid Chloride • Acetic anhydride is cheaper, gives a better yield than acetyl chloride. • Use acetic formic anhydride to produce formate esters and formamides. • Use cyclic anhydrides to produce a difunctional molecule. Chapter 21

  19. acid acid chloride acid anhydride => methyl ester Synthesis of Esters Chapter 21

  20. 3° alcohol => Reactions of Esters acid ester amide 1° alcohol Chapter 21

  21. => Lactones • Formation favored for five- and six-membered rings. • For larger rings, remove water to shift equilibrium toward products Chapter 21

  22. Dacron® thread Mylar® tape Glyptal resin PET bottles => Polyesters Chapter 21

  23. acid acid chloride acid anhydride ester => nitrile Synthesis of Amides Chapter 21

  24. nitrile => Reactions of Amides acid and amine amine 1° amine Chapter 21

  25. Lactam Formation • Five- and six-membered rings can be formed by heating - and -amino acids. • Smaller or larger rings do not form readily. => Chapter 21

  26. Amide  ester !! => -Lactams • Highly reactive, 4-membered ring. • Found in antibiotics isolated from fungi. Chapter 21

  27. Polyamides Nylon 6.6 => Chapter 21

  28. 1° amide alkyl halide diazonium salt aldehyde or ketone cyanohydrin => Synthesis of Nitriles Chapter 21

  29. amide acid ketone => Reactions of Nitriles 1° amine Chapter 21

  30. => Thioesters More reactive than esters because: • -S-R is a better leaving group than -O-R • Resonance overlap is not as effective. Chapter 21

  31. phosgene => Carbonic Acid Esters • CO2 in water contains some H2CO3. • Diesters are stable. • Synthesized from phosgene. Chapter 21

  32. => Urea and Urethanes • Urea is the diamide of carbonic acid. • Urethanes are esters of a monoamide of carbonic acid. Chapter 21

  33. => Polycarbonates Long-chain esters of carbonic acid Chapter 21

  34. => Polyurethanes A diol reacts with a diisocyanate. Chapter 21

  35. End of Chapter 21 Chapter 21

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